Effect Of Chelating Agent On Phytoremediation Of Cadmium And Arsenic Compound Contaminated Farmland

In China,Over 20 million hectares of land have been attacked by heavy metals,such as Cd,As,Hg,and Zn.The heavy metal pollution of farmland is particularly serious,because the long-term process of heavy metal pollution in soil is convert and irreversible,which affects the entire land ecology and underground natural water systemand seriously affects the yield and quality of crops.Heavy metals can be accumulated in the edible part of crops after being absorbed from the contaminated soil,enter the human body through the food chain,and cause serious harm to human health.For the government and application of heavy metal contaminated soil in practice,a field experiment method was used to improv the efficiency of plant extraction for heavy metals from soil by applying chelating agents in this study,and studied the effect of different chelating agents(EDTA,EGTA,EDDS and NTA)on the phytoremediation by four plants(oil sunflower,Bidens?xanthium?radix phytolaccae)to Cd and As contaminated farmland soil.The main findings are as follows:(1)The treatment with different chelating agents EDTA,EGTA,EDDS and NTA had no significant impact on the biomass of the whole sunflower plant and its organs,nor did it have significant effects on the yield of Bidens,Xanthium and Radix phytolaccae.Among them,Bidens had the highest yield due to the growth density.(2)Different chelating agents had different effects on the content and accumulation of Cd and As in organs of Bidens,xanthium,radix phytolaccae and oil sunflower.The application of chelating agents led a significant increase of Cd content in the overground part of Bidens niduscompared with CK treatment,with an increase of 167.2%?219.1%;for the aboveground of xanthium,the application of EDTA and EDDS influence was larger,and increased by 242.8%and 235.3%compared with CK,respectively.followed by NTA and EDDS,increased by 134.5%and 100.6%respectively;the application of chelating agents had significant effects on the stems and leaves of phytolaccae;As was mainly accumulated in the ground part of Bidens,xanthium and radix phytolaccae plants the application of EDTA and EDDS increased of As content by 49.4%and 100.0%compared with CK significantly;compared with CK treatment,the application of four chelating agents led to an increase of 30.2%?55.1%of Cd content in oil sunflower disk,As contentin root system increased by 15.4%?23.6%,and had no significant effect on Cd content of oil sunflower seeds and stems.(3)The accumulation of Cd per acre of Bidens,xanthium and radix phytolaccae after treatment was increased compared with CK,and it was increased by 246.8%,200.9%and 68.4%,respectively.The accumulation of grass acres is as high as 0.002kg/hm~2.The treatment with 4 chelating agents increased the total Cd accumulation of oil sunflower plants by 32.8%?45.3%compared with CK treatment,but had no significant effect on the accumulation of As in oil sunflower.